kolan
/
CMake
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity
CMake/Utilities/cmlibarchive/libarchive/archive_read.c

1242 lines
38 KiB
C
Raw Blame History

/*-
* Copyright (c) 2003-2007 Tim Kientzle
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This file contains the "essential" portions of the read API, that
* is, stuff that will probably always be used by any client that
* actually needs to read an archive. Optional pieces have been, as
* far as possible, separated out into separate files to avoid
* needlessly bloating statically-linked clients.
*/
#include "archive_platform.h"
__FBSDID("$FreeBSD: src/lib/libarchive/archive_read.c,v 1.39 2008/12/06 06:45:15 kientzle Exp $");
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#include <stdio.h>
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "archive.h"
#include "archive_entry.h"
#include "archive_private.h"
#include "archive_read_private.h"
#define minimum(a, b) (a < b ? a : b)
static int build_stream(struct archive_read *);
static int choose_format(struct archive_read *);
static struct archive_vtable *archive_read_vtable(void);
static int _archive_read_close(struct archive *);
static int _archive_read_finish(struct archive *);
static struct archive_vtable *
archive_read_vtable(void)
{
static struct archive_vtable av;
static int inited = 0;
if (!inited) {
av.archive_finish = _archive_read_finish;
av.archive_close = _archive_read_close;
}
return (&av);
}
/*
* Allocate, initialize and return a struct archive object.
*/
struct archive *
archive_read_new(void)
{
struct archive_read *a;
a = (struct archive_read *)malloc(sizeof(*a));
if (a == NULL)
return (NULL);
memset(a, 0, sizeof(*a));
a->archive.magic = ARCHIVE_READ_MAGIC;
a->archive.state = ARCHIVE_STATE_NEW;
a->entry = archive_entry_new();
a->archive.vtable = archive_read_vtable();
return (&a->archive);
}
/*
* Record the do-not-extract-to file. This belongs in archive_read_extract.c.
*/
void
archive_read_extract_set_skip_file(struct archive *_a, dev_t d, ino_t i)
{
struct archive_read *a = (struct archive_read *)_a;
__archive_check_magic(_a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_ANY,
"archive_read_extract_set_skip_file");
a->skip_file_dev = d;
a->skip_file_ino = i;
}
/*
* Set read options for the format.
*/
int
archive_read_set_format_options(struct archive *_a, const char *s)
{
struct archive_read *a;
struct archive_format_descriptor *format;
char key[64], val[64];
char *valp;
size_t i;
int len, r;
__archive_check_magic(_a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_NEW,
"archive_read_set_format_options");
if (s == NULL || *s == '\0')
return (ARCHIVE_OK);
a = (struct archive_read *)_a;
__archive_check_magic(&a->archive, ARCHIVE_READ_MAGIC,
ARCHIVE_STATE_NEW, "archive_read_set_format_options");
len = 0;
for (i = 0; i < sizeof(a->formats)/sizeof(a->formats[0]); i++) {
format = &a->formats[i];
if (format == NULL || format->options == NULL ||
format->name == NULL)
/* This format does not support option. */
continue;
while ((len = __archive_parse_options(s, format->name,
sizeof(key), key, sizeof(val), val)) > 0) {
valp = val[0] == '\0' ? NULL : val;
a->format = format;
r = format->options(a, key, valp);
a->format = NULL;
if (r == ARCHIVE_FATAL)
return (r);
s += len;
}
}
if (len < 0) {
archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
"Illegal format options.");
return (ARCHIVE_WARN);
}
return (ARCHIVE_OK);
}
/*
* Set read options for the filter.
*/
int
archive_read_set_filter_options(struct archive *_a, const char *s)
{
struct archive_read *a;
struct archive_read_filter *filter;
struct archive_read_filter_bidder *bidder;
char key[64], val[64];
int len, r;
__archive_check_magic(_a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_NEW,
"archive_read_set_filter_options");
if (s == NULL || *s == '\0')
return (ARCHIVE_OK);
a = (struct archive_read *)_a;
__archive_check_magic(&a->archive, ARCHIVE_READ_MAGIC,
ARCHIVE_STATE_NEW, "archive_read_set_filter_options");
filter = a->filter;
len = 0;
for (filter = a->filter; filter != NULL; filter = filter->upstream) {
bidder = filter->bidder;
if (bidder == NULL)
continue;
if (bidder->options == NULL)
/* This bidder does not support option */
continue;
while ((len = __archive_parse_options(s, filter->name,
sizeof(key), key, sizeof(val), val)) > 0) {
if (val[0] == '\0')
r = bidder->options(bidder, key, NULL);
else
r = bidder->options(bidder, key, val);
if (r == ARCHIVE_FATAL)
return (r);
s += len;
}
}
if (len < 0) {
archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
"Illegal format options.");
return (ARCHIVE_WARN);
}
return (ARCHIVE_OK);
}
/*
* Set read options for the format and the filter.
*/
int
archive_read_set_options(struct archive *_a, const char *s)
{
int r;
__archive_check_magic(_a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_NEW,
"archive_read_set_options");
archive_clear_error(_a);
r = archive_read_set_format_options(_a, s);
if (r != ARCHIVE_OK)
return (r);
r = archive_read_set_filter_options(_a, s);
if (r != ARCHIVE_OK)
return (r);
return (ARCHIVE_OK);
}
/*
* Open the archive
*/
int
archive_read_open(struct archive *a, void *client_data,
archive_open_callback *client_opener, archive_read_callback *client_reader,
archive_close_callback *client_closer)
{
/* Old archive_read_open() is just a thin shell around
* archive_read_open2. */
return archive_read_open2(a, client_data, client_opener,
client_reader, NULL, client_closer);
}
static ssize_t
client_read_proxy(struct archive_read_filter *self, const void **buff)
{
ssize_t r;
r = (self->archive->client.reader)(&self->archive->archive,
self->data, buff);
self->archive->archive.raw_position += r;
return (r);
}
static int64_t
client_skip_proxy(struct archive_read_filter *self, int64_t request)
{
int64_t ask, get, total;
/* Limit our maximum seek request to 1GB on platforms
* with 32-bit off_t (such as Windows). */
int64_t skip_limit = ((int64_t)1) << (sizeof(off_t) * 8 - 2);
if (self->archive->client.skipper == NULL)
return (0);
total = 0;
for (;;) {
ask = request;
if (ask > skip_limit)
ask = skip_limit;
get = (self->archive->client.skipper)(&self->archive->archive,
self->data, ask);
if (get == 0)
return (total);
request -= get;
self->archive->archive.raw_position += get;
total += get;
}
}
static int
client_close_proxy(struct archive_read_filter *self)
{
int r = ARCHIVE_OK;
if (self->archive->client.closer != NULL)
r = (self->archive->client.closer)((struct archive *)self->archive,
self->data);
self->data = NULL;
return (r);
}
int
archive_read_open2(struct archive *_a, void *client_data,
archive_open_callback *client_opener,
archive_read_callback *client_reader,
archive_skip_callback *client_skipper,
archive_close_callback *client_closer)
{
struct archive_read *a = (struct archive_read *)_a;
struct archive_read_filter *filter;
int e;
__archive_check_magic(_a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_NEW,
"archive_read_open");
archive_clear_error(&a->archive);
if (client_reader == NULL)
__archive_errx(1,
"No reader function provided to archive_read_open");
/* Open data source. */
if (client_opener != NULL) {
e =(client_opener)(&a->archive, client_data);
if (e != 0) {
/* If the open failed, call the closer to clean up. */
if (client_closer)
(client_closer)(&a->archive, client_data);
return (e);
}
}
/* Save the client functions and mock up the initial source. */
a->client.reader = client_reader;
a->client.skipper = client_skipper;
a->client.closer = client_closer;
filter = calloc(1, sizeof(*filter));
if (filter == NULL)
return (ARCHIVE_FATAL);
filter->bidder = NULL;
filter->upstream = NULL;
filter->archive = a;
filter->data = client_data;
filter->read = client_read_proxy;
filter->skip = client_skip_proxy;
filter->close = client_close_proxy;
filter->name = "none";
filter->code = ARCHIVE_COMPRESSION_NONE;
a->filter = filter;
/* Build out the input pipeline. */
e = build_stream(a);
if (e == ARCHIVE_OK)
a->archive.state = ARCHIVE_STATE_HEADER;
return (e);
}
/*
* Allow each registered stream transform to bid on whether
* it wants to handle this stream. Repeat until we've finished
* building the pipeline.
*/
static int
build_stream(struct archive_read *a)
{
int number_bidders, i, bid, best_bid;
struct archive_read_filter_bidder *bidder, *best_bidder;
struct archive_read_filter *filter;
ssize_t avail;
int r;
for (;;) {
number_bidders = sizeof(a->bidders) / sizeof(a->bidders[0]);
best_bid = 0;
best_bidder = NULL;
bidder = a->bidders;
for (i = 0; i < number_bidders; i++, bidder++) {
if (bidder->bid != NULL) {
bid = (bidder->bid)(bidder, a->filter);
if (bid > best_bid) {
best_bid = bid;
best_bidder = bidder;
}
}
}
/* If no bidder, we're done. */
if (best_bidder == NULL) {
a->archive.compression_name = a->filter->name;
a->archive.compression_code = a->filter->code;
return (ARCHIVE_OK);
}
filter
= (struct archive_read_filter *)calloc(1, sizeof(*filter));
if (filter == NULL)
return (ARCHIVE_FATAL);
filter->bidder = best_bidder;
filter->archive = a;
filter->upstream = a->filter;
r = (best_bidder->init)(filter);
if (r != ARCHIVE_OK) {
free(filter);
return (r);
}
/* Verify the filter by asking it for some data. */
__archive_read_filter_ahead(filter, 1, &avail);
if (avail < 0) {
/* If the read failed, bail out now. */
free(filter);
return (avail);
}
a->filter = filter;
}
}
/*
* Read header of next entry.
*/
int
archive_read_next_header2(struct archive *_a, struct archive_entry *entry)
{
struct archive_read *a = (struct archive_read *)_a;
int slot, ret;
__archive_check_magic(_a, ARCHIVE_READ_MAGIC,
ARCHIVE_STATE_HEADER | ARCHIVE_STATE_DATA,
"archive_read_next_header");
++_a->file_count;
archive_entry_clear(entry);
archive_clear_error(&a->archive);
/*
* If no format has yet been chosen, choose one.
*/
if (a->format == NULL) {
slot = choose_format(a);
if (slot < 0) {
a->archive.state = ARCHIVE_STATE_FATAL;
return (ARCHIVE_FATAL);
}
a->format = &(a->formats[slot]);
}
/*
* If client didn't consume entire data, skip any remainder
* (This is especially important for GNU incremental directories.)
*/
if (a->archive.state == ARCHIVE_STATE_DATA) {
ret = archive_read_data_skip(&a->archive);
if (ret == ARCHIVE_EOF) {
archive_set_error(&a->archive, EIO, "Premature end-of-file.");
a->archive.state = ARCHIVE_STATE_FATAL;
return (ARCHIVE_FATAL);
}
if (ret != ARCHIVE_OK)
return (ret);
}
/* Record start-of-header. */
a->header_position = a->archive.file_position;
ret = (a->format->read_header)(a, entry);
/*
* EOF and FATAL are persistent at this layer. By
* modifying the state, we guarantee that future calls to
* read a header or read data will fail.
*/
switch (ret) {
case ARCHIVE_EOF:
a->archive.state = ARCHIVE_STATE_EOF;
break;
case ARCHIVE_OK:
a->archive.state = ARCHIVE_STATE_DATA;
break;
case ARCHIVE_WARN:
a->archive.state = ARCHIVE_STATE_DATA;
break;
case ARCHIVE_RETRY:
break;
case ARCHIVE_FATAL:
a->archive.state = ARCHIVE_STATE_FATAL;
break;
}
a->read_data_output_offset = 0;
a->read_data_remaining = 0;
return (ret);
}
int
archive_read_next_header(struct archive *_a, struct archive_entry **entryp)
{
int ret;
struct archive_read *a = (struct archive_read *)_a;
*entryp = NULL;
ret = archive_read_next_header2(_a, a->entry);
*entryp = a->entry;
return ret;
}
/*
* Allow each registered format to bid on whether it wants to handle
* the next entry. Return index of winning bidder.
*/
static int
choose_format(struct archive_read *a)
{
int slots;
int i;
int bid, best_bid;
int best_bid_slot;
slots = sizeof(a->formats) / sizeof(a->formats[0]);
best_bid = -1;
best_bid_slot = -1;
/* Set up a->format and a->pformat_data for convenience of bidders. */
a->format = &(a->formats[0]);
for (i = 0; i < slots; i++, a->format++) {
if (a->format->bid) {
bid = (a->format->bid)(a);
if (bid == ARCHIVE_FATAL)
return (ARCHIVE_FATAL);
if ((bid > best_bid) || (best_bid_slot < 0)) {
best_bid = bid;
best_bid_slot = i;
}
}
}
/*
* There were no bidders; this is a serious programmer error
* and demands a quick and definitive abort.
*/
if (best_bid_slot < 0)
__archive_errx(1, "No formats were registered; you must "
"invoke at least one archive_read_support_format_XXX "
"function in order to successfully read an archive.");
/*
* There were bidders, but no non-zero bids; this means we
* can't support this stream.
*/
if (best_bid < 1) {
archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
"Unrecognized archive format");
return (ARCHIVE_FATAL);
}
return (best_bid_slot);
}
/*
* Return the file offset (within the uncompressed data stream) where
* the last header started.
*/
int64_t
archive_read_header_position(struct archive *_a)
{
struct archive_read *a = (struct archive_read *)_a;
__archive_check_magic(_a, ARCHIVE_READ_MAGIC,
ARCHIVE_STATE_ANY, "archive_read_header_position");
return (a->header_position);
}
/*
* Read data from an archive entry, using a read(2)-style interface.
* This is a convenience routine that just calls
* archive_read_data_block and copies the results into the client
* buffer, filling any gaps with zero bytes. Clients using this
* API can be completely ignorant of sparse-file issues; sparse files
* will simply be padded with nulls.
*
* DO NOT intermingle calls to this function and archive_read_data_block
* to read a single entry body.
*/
ssize_t
archive_read_data(struct archive *_a, void *buff, size_t s)
{
struct archive_read *a = (struct archive_read *)_a;
char *dest;
const void *read_buf;
size_t bytes_read;
size_t len;
int r;
bytes_read = 0;
dest = (char *)buff;
while (s > 0) {
if (a->read_data_remaining == 0) {
read_buf = a->read_data_block;
r = archive_read_data_block(&a->archive, &read_buf,
&a->read_data_remaining, &a->read_data_offset);
a->read_data_block = read_buf;
if (r == ARCHIVE_EOF)
return (bytes_read);
/*
* Error codes are all negative, so the status
* return here cannot be confused with a valid
* byte count. (ARCHIVE_OK is zero.)
*/
if (r < ARCHIVE_OK)
return (r);
}
if (a->read_data_offset < a->read_data_output_offset) {
archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
"Encountered out-of-order sparse blocks");
return (ARCHIVE_RETRY);
}
/* Compute the amount of zero padding needed. */
if (a->read_data_output_offset + (off_t)s <
a->read_data_offset) {
len = s;
} else if (a->read_data_output_offset <
a->read_data_offset) {
len = a->read_data_offset -
a->read_data_output_offset;
} else
len = 0;
/* Add zeroes. */
memset(dest, 0, len);
s -= len;
a->read_data_output_offset += len;
dest += len;
bytes_read += len;
/* Copy data if there is any space left. */
if (s > 0) {
len = a->read_data_remaining;
if (len > s)
len = s;
memcpy(dest, a->read_data_block, len);
s -= len;
a->read_data_block += len;
a->read_data_remaining -= len;
a->read_data_output_offset += len;
a->read_data_offset += len;
dest += len;
bytes_read += len;
}
}
return (bytes_read);
}
#if ARCHIVE_API_VERSION < 3
/*
* Obsolete function provided for compatibility only. Note that the API
* of this function doesn't allow the caller to detect if the remaining
* data from the archive entry is shorter than the buffer provided, or
* even if an error occurred while reading data.
*/
int
archive_read_data_into_buffer(struct archive *a, void *d, ssize_t len)
{
archive_read_data(a, d, len);
return (ARCHIVE_OK);
}
#endif
/*
* Skip over all remaining data in this entry.
*/
int
archive_read_data_skip(struct archive *_a)
{
struct archive_read *a = (struct archive_read *)_a;
int r;
const void *buff;
size_t size;
off_t offset;
__archive_check_magic(_a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_DATA,
"archive_read_data_skip");
if (a->format->read_data_skip != NULL)
r = (a->format->read_data_skip)(a);
else {
while ((r = archive_read_data_block(&a->archive,
&buff, &size, &offset))
== ARCHIVE_OK)
;
}
if (r == ARCHIVE_EOF)
r = ARCHIVE_OK;
a->archive.state = ARCHIVE_STATE_HEADER;
return (r);
}
/*
* Read the next block of entry data from the archive.
* This is a zero-copy interface; the client receives a pointer,
* size, and file offset of the next available block of data.
*
* Returns ARCHIVE_OK if the operation is successful, ARCHIVE_EOF if
* the end of entry is encountered.
*/
int
archive_read_data_block(struct archive *_a,
const void **buff, size_t *size, off_t *offset)
{
struct archive_read *a = (struct archive_read *)_a;
__archive_check_magic(_a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_DATA,
"archive_read_data_block");
if (a->format->read_data == NULL) {
archive_set_error(&a->archive, ARCHIVE_ERRNO_PROGRAMMER,
"Internal error: "
"No format_read_data_block function registered");
return (ARCHIVE_FATAL);
}
return (a->format->read_data)(a, buff, size, offset);
}
/*
* Close the file and release most resources.
*
* Be careful: client might just call read_new and then read_finish.
* Don't assume we actually read anything or performed any non-trivial
* initialization.
*/
static int
_archive_read_close(struct archive *_a)
{
struct archive_read *a = (struct archive_read *)_a;
int r = ARCHIVE_OK, r1 = ARCHIVE_OK;
size_t i, n;
__archive_check_magic(&a->archive, ARCHIVE_READ_MAGIC,
ARCHIVE_STATE_ANY, "archive_read_close");
archive_clear_error(&a->archive);
a->archive.state = ARCHIVE_STATE_CLOSED;
/* Call cleanup functions registered by optional components. */
if (a->cleanup_archive_extract != NULL)
r = (a->cleanup_archive_extract)(a);
/* TODO: Clean up the formatters. */
/* Clean up the filter pipeline. */
while (a->filter != NULL) {
struct archive_read_filter *t = a->filter->upstream;
if (a->filter->close != NULL) {
r1 = (a->filter->close)(a->filter);
if (r1 < r)
r = r1;
}
free(a->filter->buffer);
free(a->filter);
a->filter = t;
}
/* Release the bidder objects. */
n = sizeof(a->bidders)/sizeof(a->bidders[0]);
for (i = 0; i < n; i++) {
if (a->bidders[i].free != NULL) {
r1 = (a->bidders[i].free)(&a->bidders[i]);
if (r1 < r)
r = r1;
}
}
return (r);
}
/*
* Release memory and other resources.
*/
static int
_archive_read_finish(struct archive *_a)
{
struct archive_read *a = (struct archive_read *)_a;
int i;
int slots;
int r = ARCHIVE_OK;
__archive_check_magic(_a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_ANY,
"archive_read_finish");
if (a->archive.state != ARCHIVE_STATE_CLOSED)
r = archive_read_close(&a->archive);
/* Cleanup format-specific data. */
slots = sizeof(a->formats) / sizeof(a->formats[0]);
for (i = 0; i < slots; i++) {
a->format = &(a->formats[i]);
if (a->formats[i].cleanup)
(a->formats[i].cleanup)(a);
}
archive_string_free(&a->archive.error_string);
if (a->entry)
archive_entry_free(a->entry);
a->archive.magic = 0;
free(a);
#if ARCHIVE_API_VERSION > 1
return (r);
#endif
}
/*
* Used internally by read format handlers to register their bid and
* initialization functions.
*/
int
__archive_read_register_format(struct archive_read *a,
void *format_data,
const char *name,
int (*bid)(struct archive_read *),
int (*options)(struct archive_read *, const char *, const char *),
int (*read_header)(struct archive_read *, struct archive_entry *),
int (*read_data)(struct archive_read *, const void **, size_t *, off_t *),
int (*read_data_skip)(struct archive_read *),
int (*cleanup)(struct archive_read *))
{
int i, number_slots;
__archive_check_magic(&a->archive,
ARCHIVE_READ_MAGIC, ARCHIVE_STATE_NEW,
"__archive_read_register_format");
number_slots = sizeof(a->formats) / sizeof(a->formats[0]);
for (i = 0; i < number_slots; i++) {
if (a->formats[i].bid == bid)
return (ARCHIVE_WARN); /* We've already installed */
if (a->formats[i].bid == NULL) {
a->formats[i].bid = bid;
a->formats[i].options = options;
a->formats[i].read_header = read_header;
a->formats[i].read_data = read_data;
a->formats[i].read_data_skip = read_data_skip;
a->formats[i].cleanup = cleanup;
a->formats[i].data = format_data;
a->formats[i].name = name;
return (ARCHIVE_OK);
}
}
__archive_errx(1, "Not enough slots for format registration");
return (ARCHIVE_FATAL); /* Never actually called. */
}
/*
* Used internally by decompression routines to register their bid and
* initialization functions.
*/
struct archive_read_filter_bidder *
__archive_read_get_bidder(struct archive_read *a)
{
int i, number_slots;
__archive_check_magic(&a->archive,
ARCHIVE_READ_MAGIC, ARCHIVE_STATE_NEW,
"__archive_read_get_bidder");
number_slots = sizeof(a->bidders) / sizeof(a->bidders[0]);
for (i = 0; i < number_slots; i++) {
if (a->bidders[i].bid == NULL) {
memset(a->bidders + i, 0, sizeof(a->bidders[0]));
return (a->bidders + i);
}
}
__archive_errx(1, "Not enough slots for compression registration");
return (NULL); /* Never actually executed. */
}
/*
* The next three functions comprise the peek/consume internal I/O
* system used by archive format readers. This system allows fairly
* flexible read-ahead and allows the I/O code to operate in a
* zero-copy manner most of the time.
*
* In the ideal case, filters generate blocks of data
* and __archive_read_ahead() just returns pointers directly into
* those blocks. Then __archive_read_consume() just bumps those
* pointers. Only if your request would span blocks does the I/O
* layer use a copy buffer to provide you with a contiguous block of
* data. The __archive_read_skip() is an optimization; it scans ahead
* very quickly (it usually translates into a seek() operation if
* you're reading uncompressed disk files).
*
* A couple of useful idioms:
* * "I just want some data." Ask for 1 byte and pay attention to
* the "number of bytes available" from __archive_read_ahead().
* You can consume more than you asked for; you just can't consume
* more than is available. If you consume everything that's
* immediately available, the next read_ahead() call will pull
* the next block.
* * "I want to output a large block of data." As above, ask for 1 byte,
* emit all that's available (up to whatever limit you have), then
* repeat until you're done.
* * "I want to peek ahead by a large amount." Ask for 4k or so, then
* double and repeat until you get an error or have enough. Note
* that the I/O layer will likely end up expanding its copy buffer
* to fit your request, so use this technique cautiously. This
* technique is used, for example, by some of the format tasting
* code that has uncertain look-ahead needs.
*
* TODO: Someday, provide a more generic __archive_read_seek() for
* those cases where it's useful. This is tricky because there are lots
* of cases where seek() is not available (reading gzip data from a
* network socket, for instance), so there needs to be a good way to
* communicate whether seek() is available and users of that interface
* need to use non-seeking strategies whenever seek() is not available.
*/
/*
* Looks ahead in the input stream:
* * If 'avail' pointer is provided, that returns number of bytes available
* in the current buffer, which may be much larger than requested.
* * If end-of-file, *avail gets set to zero.
* * If error, *avail gets error code.
* * If request can be met, returns pointer to data, returns NULL
* if request is not met.
*
* Note: If you just want "some data", ask for 1 byte and pay attention
* to *avail, which will have the actual amount available. If you
* know exactly how many bytes you need, just ask for that and treat
* a NULL return as an error.
*
* Important: This does NOT move the file pointer. See
* __archive_read_consume() below.
*/
/*
* This is tricky. We need to provide our clients with pointers to
* contiguous blocks of memory but we want to avoid copying whenever
* possible.
*
* Mostly, this code returns pointers directly into the block of data
* provided by the client_read routine. It can do this unless the
* request would split across blocks. In that case, we have to copy
* into an internal buffer to combine reads.
*/
const void *
__archive_read_ahead(struct archive_read *a, size_t min, ssize_t *avail)
{
return (__archive_read_filter_ahead(a->filter, min, avail));
}
const void *
__archive_read_filter_ahead(struct archive_read_filter *filter,
size_t min, ssize_t *avail)
{
ssize_t bytes_read;
size_t tocopy;
if (filter->fatal) {
if (avail)
*avail = ARCHIVE_FATAL;
return (NULL);
}
/*
* Keep pulling more data until we can satisfy the request.
*/
for (;;) {
/*
* If we can satisfy from the copy buffer (and the
* copy buffer isn't empty), we're done. In particular,
* note that min == 0 is a perfectly well-defined
* request.
*/
if (filter->avail >= min && filter->avail > 0) {
if (avail != NULL)
*avail = filter->avail;
return (filter->next);
}
/*
* We can satisfy directly from client buffer if everything
* currently in the copy buffer is still in the client buffer.
*/
if (filter->client_total >= filter->client_avail + filter->avail
&& filter->client_avail + filter->avail >= min) {
/* "Roll back" to client buffer. */
filter->client_avail += filter->avail;
filter->client_next -= filter->avail;
/* Copy buffer is now empty. */
filter->avail = 0;
filter->next = filter->buffer;
/* Return data from client buffer. */
if (avail != NULL)
*avail = filter->client_avail;
return (filter->client_next);
}
/* Move data forward in copy buffer if necessary. */
if (filter->next > filter->buffer &&
filter->next + min > filter->buffer + filter->buffer_size) {
if (filter->avail > 0)
memmove(filter->buffer, filter->next, filter->avail);
filter->next = filter->buffer;
}
/* If we've used up the client data, get more. */
if (filter->client_avail <= 0) {
if (filter->end_of_file) {
if (avail != NULL)
*avail = 0;
return (NULL);
}
bytes_read = (filter->read)(filter,
&filter->client_buff);
if (bytes_read < 0) { /* Read error. */
filter->client_total = filter->client_avail = 0;
filter->client_next = filter->client_buff = NULL;
filter->fatal = 1;
if (avail != NULL)
*avail = ARCHIVE_FATAL;
return (NULL);
}
if (bytes_read == 0) { /* Premature end-of-file. */
filter->client_total = filter->client_avail = 0;
filter->client_next = filter->client_buff = NULL;
filter->end_of_file = 1;
/* Return whatever we do have. */
if (avail != NULL)
*avail = filter->avail;
return (NULL);
}
filter->position += bytes_read;
filter->client_total = bytes_read;
filter->client_avail = filter->client_total;
filter->client_next = filter->client_buff;
}
else
{
/*
* We can't satisfy the request from the copy
* buffer or the existing client data, so we
* need to copy more client data over to the
* copy buffer.
*/
/* Ensure the buffer is big enough. */
if (min > filter->buffer_size) {
size_t s, t;
char *p;
/* Double the buffer; watch for overflow. */
s = t = filter->buffer_size;
if (s == 0)
s = min;
while (s < min) {
t *= 2;
if (t <= s) { /* Integer overflow! */
archive_set_error(
&filter->archive->archive,
ENOMEM,
"Unable to allocate copy buffer");
filter->fatal = 1;
if (avail != NULL)
*avail = ARCHIVE_FATAL;
return (NULL);
}
s = t;
}
/* Now s >= min, so allocate a new buffer. */
p = (char *)malloc(s);
if (p == NULL) {
archive_set_error(
&filter->archive->archive,
ENOMEM,
"Unable to allocate copy buffer");
filter->fatal = 1;
if (avail != NULL)
*avail = ARCHIVE_FATAL;
return (NULL);
}
/* Move data into newly-enlarged buffer. */
if (filter->avail > 0)
memmove(p, filter->next, filter->avail);
free(filter->buffer);
filter->next = filter->buffer = p;
filter->buffer_size = s;
}
/* We can add client data to copy buffer. */
/* First estimate: copy to fill rest of buffer. */
tocopy = (filter->buffer + filter->buffer_size)
- (filter->next + filter->avail);
/* Don't waste time buffering more than we need to. */
if (tocopy + filter->avail > min)
tocopy = min - filter->avail;
/* Don't copy more than is available. */
if (tocopy > filter->client_avail)
tocopy = filter->client_avail;
memcpy(filter->next + filter->avail, filter->client_next,
tocopy);
/* Remove this data from client buffer. */
filter->client_next += tocopy;
filter->client_avail -= tocopy;
/* add it to copy buffer. */
filter->avail += tocopy;
}
}
}
/*
* Move the file pointer forward. This should be called after
* __archive_read_ahead() returns data to you. Don't try to move
* ahead by more than the amount of data available according to
* __archive_read_ahead().
*/
/*
* Mark the appropriate data as used. Note that the request here will
* often be much smaller than the size of the previous read_ahead
* request.
*/
ssize_t
__archive_read_consume(struct archive_read *a, size_t request)
{
ssize_t r;
r = __archive_read_filter_consume(a->filter, request);
a->archive.file_position += r;
return (r);
}
ssize_t
__archive_read_filter_consume(struct archive_read_filter * filter,
size_t request)
{
if (filter->avail > 0) {
/* Read came from copy buffer. */
filter->next += request;
filter->avail -= request;
} else {
/* Read came from client buffer. */
filter->client_next += request;
filter->client_avail -= request;
}
return (request);
}
/*
* Move the file pointer ahead by an arbitrary amount. If you're
* reading uncompressed data from a disk file, this will actually
* translate into a seek() operation. Even in cases where seek()
* isn't feasible, this at least pushes the read-and-discard loop
* down closer to the data source.
*/
int64_t
__archive_read_skip(struct archive_read *a, int64_t request)
{
int64_t skipped = __archive_read_skip_lenient(a, request);
if (skipped == request)
return (skipped);
/* We hit EOF before we satisfied the skip request. */
if (skipped < 0) /* Map error code to 0 for error message below. */
skipped = 0;
archive_set_error(&a->archive,
ARCHIVE_ERRNO_MISC,
"Truncated input file (needed %jd bytes, only %jd available)",
(intmax_t)request, (intmax_t)skipped);
return (ARCHIVE_FATAL);
}
int64_t
__archive_read_skip_lenient(struct archive_read *a, int64_t request)
{
int64_t skipped = __archive_read_filter_skip(a->filter, request);
if (skipped > 0)
a->archive.file_position += skipped;
return (skipped);
}
int64_t
__archive_read_filter_skip(struct archive_read_filter *filter, int64_t request)
{
int64_t bytes_skipped, total_bytes_skipped = 0;
size_t min;
if (filter->fatal)
return (-1);
/*
* If there is data in the buffers already, use that first.
*/
if (filter->avail > 0) {
min = minimum(request, (off_t)filter->avail);
bytes_skipped = __archive_read_filter_consume(filter, min);
request -= bytes_skipped;
total_bytes_skipped += bytes_skipped;
}
if (filter->client_avail > 0) {
min = minimum(request, (int64_t)filter->client_avail);
bytes_skipped = __archive_read_filter_consume(filter, min);
request -= bytes_skipped;
total_bytes_skipped += bytes_skipped;
}
if (request == 0)
return (total_bytes_skipped);
/*
* If a client_skipper was provided, try that first.
*/
#if ARCHIVE_API_VERSION < 2
if ((filter->skip != NULL) && (request < SSIZE_MAX)) {
#else
if (filter->skip != NULL) {
#endif
bytes_skipped = (filter->skip)(filter, request);
if (bytes_skipped < 0) { /* error */
filter->client_total = filter->client_avail = 0;
filter->client_next = filter->client_buff = NULL;
filter->fatal = 1;
return (bytes_skipped);
}
total_bytes_skipped += bytes_skipped;
request -= bytes_skipped;
filter->client_next = filter->client_buff;
filter->client_avail = filter->client_total = 0;
}
/*
* Note that client_skipper will usually not satisfy the
* full request (due to low-level blocking concerns),
* so even if client_skipper is provided, we may still
* have to use ordinary reads to finish out the request.
*/
while (request > 0) {
const void* dummy_buffer;
ssize_t bytes_read;
dummy_buffer = __archive_read_filter_ahead(filter,
1, &bytes_read);
if (bytes_read < 0)
return (bytes_read);
if (bytes_read == 0) {
return (total_bytes_skipped);
}
min = (size_t)(minimum(bytes_read, request));
bytes_read = __archive_read_filter_consume(filter, min);
total_bytes_skipped += bytes_read;
request -= bytes_read;
}
return (total_bytes_skipped);
}
Reference in New Issue View Git Blame Copy Permalink